I'm trying to automate a build for a web application that uses around 400 perl modules, to run on redhat enterprise 6 servers. I'm running into some difficulties:

Can’t use rpms directly because even Dag::Wiers only has about half of the rpms we need. Can’t mix rpm installs and cpan installs because updates of either could break modules installed with the other.

Can’t use cpan command line in an automated build since it asks interactive questions.

I can't find an rpm for cpanm on RHEL6/Centos6. So I tried installing it using cpan, but it requires more recent versions of prereq modules than what the latest update of redhat 6 provides, and the build of these fails.

After all these years and perl module installation on a standard OS is still so difficult? What am I doing wrong?

Can’t use cpan command line in an automated build since it asks interactive questions.

The only interactive questions I know about are the ones asking for confirmation to install each missing prereq as they are discovered. The simple solution is to properly configure cpan so that it doesn't ask you that confirmation.